1. Field of the Invention
This invention in general comprises an apparatus and method for generating electrostatically charged vapor and/or aerosols from a selected family of liquids. It is intended to be used to treat or condition the air of an occupied space or building by introducing vapors which have a pleasant aroma and may also have a biocidal or biostatic effect within a building's ventilation system duct work and air handling components. It is believed that the electrostatically charged vapors and aerosols will have a greater effect upon the treatment of the air within buildings. The apparatus and methods used herein may be used to treat or condition air either by direct discharge into an enclosed space or by release of charged, conditioning vapors into air handling ducts.
There is a growing concern in the area of indoor air quality often referred to as "sick building syndrome." The modern living and working environment has been designed around energy efficiency and not so oriented around occupant health and comfort. It would be desirable to be able to recreate the properties of fresh outdoor air, indoors. Over the last five years there has also been an increased interest in aromatic essences from plants and their application to enhancing or altering the quality of indoor environment.
The primary function of the apparatus is based upon the principles outlined in the above-identified, copending U.S. patent application.
By applying a high voltage DC charge to a semiconductive, capillament assembly which receives the selected liquid, electrostatically charged vapor and aerosols will be released. This device is referred to throughout this disclosure as a "vaporizing emitter." This invention has a particular application in the vaporization of essential oils commonly used in the fragrance industry. Essential oils derived from plants, trees and flowers, also perfumes, natural and synthetic; deodorants, disinfectants, fumigants, fungicides, insecticides, and other liquid substances which are primarily hydrocarbon based which may be intended to modify, condition, or alter the quality of an indoor or outdoor atmosphere can be vaporized more effectively using this apparatus.
The vaporization of liquids is known to be accomplished by a variety of devices and there are also many devices which use electrostatic means to generate aerosols. This invention is directed to the generation of vapor and/or aerosols more efficiently from a variety of liquids with more control than the prior art.
2. Prior Art
The closest prior art was found to be an apparatus for generating a mist of negatively charged liquid aerosols, as disclosed by Michalchik in U.S. Pat. No. 4,776,515. The limitations of the patent are that a very specific conductivity of the liquid is required and that charged particles are generated, not a vapor. The device also has specific requirements upon the manner in which the liquid is fed to the capillary in order to maintain the desired aerosol generating effect.
An apparatus for producing a spray of liquid droplets of a specific size range is disclosed in U.S. Pat. No. 4,829,996. This device is specific to the production of particles by electrostatic means of a certain size and specifically not a vapor. This device is specifically an electrostatic spray generator for an inhaler.
The electrostatic dispersal of liquids by Pollard et al in U.S. Pat. No. 4,400,332 is specific in the use of a porous material having a series of termini which is fed a liquid, namely petrol fuels. This porous material is charged electrostatically and a spray of fine particles is formed in an air stream. This device produces very fine particles within an air stream wherein an annular enclosure is required. Here again vapor is not mentioned and a moving air stream is required.
Electrostatic enhancement of evaporation by French et al in U.S. Pat. No. 3,771,233 involves a method of specifically improving the evaporation of water from investment cast ceramic molds using an electrostatic charge placed upon the mold. The evaporation process is enhanced with a series of needles of an opposite charge placed near the surface of the mold. This method is specific to the evaporation of water from investment castings. In this case, evaporating water is the only objective.
This invention is an improvement upon these methods and others such that both vapor and/or aerosols can be generated from the same device. Another advantage is that the rate of vapor generation can be controlled by the adjustment of the voltage applied to the "emitter," and/or by the liquid feed rate and/or the placement of an electrostatic field forming control grid near the emitter.